The advent of small battery powered electronic devices increases the need for decreasing power consumption in most aspects of the electronic circuitry. This includes the operation of microcontrollers, data conversion by analog interface converters and power converters that drive the circuits. Various methods have been used to reduce power consumption including reducing the power supply voltage, reducing the capacitive loading of the internal and external loads, slowing the clock down in various periods and even completely powering down sections of the circuit when it is not in use.
DC-DC power converters output a selected voltage from a different voltage input. Switching power converters use metal-oxide-semiconductor field-effect-transistors (MOSFETS) that are capable of conducting relatively high currents to a load coupled to an output. To provide high current capable devices that also have a relatively low resistance, MOSFET devices referred to as “power MOSFETS” are used in the switching power converters. A power MOSFET device can be implemented using vertical MOSFET devices, and can include vertical double diffused MOSFET devices, “VDMOS”. In power converters, power reduction or power loss reduction has been achieved by several methods, including: reducing the gate drive voltage in response to the output load for the drive MOSFETS; by using multiple MOSFETS of varied sizes and only activating the most efficient sized MOSFET for a particular load current; and by changing the switching frequency during lightly loaded conditions. In each of these power loss reduction methods, additional circuitry for measuring the load current are added to achieve the power savings. The measurement circuitry and extra transistors and MOSFETS add to the complexity, cost and size of the power converters.